Finding if the mouse is over a circle is simple: you use dist() and check if the distance between the mouse and the center of the circle is below the radius of the circle.

How do you store the data for the earthquakes?
How you go about displaying that information is based entirely on how it is stored.

For example, the preferred way to do it, storing that data in a class and creating a display function to specifically display that information.

It would help if you showed your code so that we could have an idea of what you're doing and how to build off of it.